hypothalamic-pituitary axis (HPA)

embryology

• what hormones does the hypothalamus secrete 6

• what hormones does the anterior PG produce 2

• what hormones does the posterior PG produce 5

• GHRH, TRH, CRH, GnRH, dopamine, somatostatin

• vasopressin, oxytocin

• ACTH, LH, FSH, TSH, GH, PRL

what APG hormone is responsible for these conditions

• cushings disease

• secondary thyroticosis

• acromegaly

• non functioning pituitary tumour

• prolactinoma

• ACTH

• TSH

• GH

• LH/FSH

• PRL

non functioning pituitary tumours

• how common are these

• how are symptoms caused

  • what are the symptoms of this tumour

• treatment

• is it caused by excess hormone production

• majority of pituitary tumours

• due to space occupation (size and pressure on surroundings)

  • headache, vision defects, can cause PG hormone deficiency

• surgery/radiotherapy

• no

acromegaly

• what is it caused by, hormone

• symptoms

• loss of what brain part function

• how is it treated

• caused by an excess of growth hormone GH

• giant features, joint/muscle pain,nerve compression

• loss of anterior pituitary function

• treatment

  • radiotherapy

  • growth hormone receptor antagonist

prolactin

• what is this secretion inhibited by, hormone

• what is hyperprolactinaemia

• prolactin inhibiting factors PIFs

• abnormally high amounts of prolactin hormone in a person who is not breastfeeding

hyperprolactinaemia

• what are some clinical manifestations of this condition in men and women

women

• menstrual irregularity

• infertility

• galactorrhoea, production of breast milk when not breastfeeding

men

• visual abnormalities

• headache

• anterior pituitary malfunction

• galactorrhoea is uncommon

what is a common cause of prolactinomas

• what are they

• how does dopamine affect prolactin

• often drug induced

• but anything interrupting dopamine inhibitory pathway can result in hyperprolactinaemia

  • they are very common pituitary tumours

dopamine

• dopamine constantly inhibits prolactin secretion

• a sudden decrease in DA means prolactin secretion

treatment for prolactinomas

• 1 drug, 2 physical methods

• dopamine inhibits prolactin secretion and prolactin suppression can shrink the tumour

• dopamine agonists, cabergoline

• surgery, radiotherapy

hypopituitarism

• what is this

• what are main causes of them

(what is pituitary apoplexy and how does it present)

• it is a loss of pituitary function

  • pituitary tumours, compression

  • surgery

  • radiotherapy

  • pituitary infarction

  • pituitary apoplexy (haemorrhage in PG presents with a sudden headache)

adrenal gland

• what are the two types of corticoids

• mineralcorticoids

  • fluid/Na balance, aldostosterone, RAS control

• glucocorticoids

  • glucose homeostasis, cortisol, ACTH cortisol

what is cushings disease

• what is it caused by

• when the PG produces too much ACTH

• too much cortisol in the body

cushings syndroms

• what are symptoms/signs of this

• weight gain

• purple striae

• easy bruising

• central weight gain

• hypertension

• fat deposition in scapula

• proximal muscle wasting/myopathy

diagnosing cushings syndrome

• what is the difference entre cushings disease/syndrome in terms of adenoma location

• what do they screen for

• what drug is prescribed

• how is tumour location screened for

• cushings syndrome is more broad term for excess cortisol in the body, cushings disease is caused by a pituitary adenoma

• cortisol in urine

• dexamethasone

• pituitary - MRI

• adrenal - MRI

• ectoopic - MRI/CT

cushings syndroms treatment

• what are the treatment options

• surgical

• adrenolytic therapies may be used in preparation for surgery

• chemotherapy

• radiotherapy

adrenal insufficiency

• what is the name given for primary adrenocortical failure

• why is it different from secondary adrenal failure

• what is the difference between the two

• addisons disease

• excess steroid use, pituitary tumours

• primary is an autoimmune disease

addisons disease

• what are symptoms of this

  • systemic and serum

• weakness

• weight loss

• abdominal pain

• postural hypotension

• pigmentation due to ACTH hypersecretion

  • (skin, mucosa, palms, scars darken due to melanin production increase)

  • serum sodium reduced

  • urea increase, dehydration

  • serum potassium increased

what is involved in the HPT axis

hypothalamic pituitary thyroid axis

hyperthyroidism

• what is it a result of

• who is it more common in

• what does this indicate for the thyroid

• a result of excess of free T3 and T4

• more common in women

• indicates thyroid gland overactivity

what is graves disease

• what is it an example of

• what is the main sign of this

• an autoimmune disease

• makes antibodies that stimulate the thyroid

• hyperthyroidism

  • primary hyperthyroidism

• toxic multinodular goitre

what is thyrotoxicosis without hyperthyroidism

• excessive T4 administration

clinical features of hyperthyroidism

• what are treatment options

• weight loss

• increased appetite

• heat intolerance and sweating

• fatigue

• tremor

• hyperactivity, insomnia, palpatations

  • antithyroid drugs

  • radioactive iodine therapy

  • thyroidectomy

hypOthyroidism

• what are common causes (primary thyroid failure )

• autoimmune

• iodine deficiency

• antithyroid drugs

• thyroiditis

• change in TSH levels

clinical features of hypOthyroidism

• lethargy

• dry skin

• cold intolerance

• goitre

• bradycardia

• aches, pains

what does the HPG axis involve

hypothalamic pituitary gonadal axis

HPG dysfunction

• what problems will it cause in bith men and women

• in men

• in women

• problems with sexual maturation/ secondary characteristics

• delayed puberty

• short stature

men

• hypogonadism

• infertility

• erectile dysfunction

women

• infertility

• secondary amenrrhoea

• if there is an excess of a hormone in the body, what are the two places it can come from

• name 3 pituitary gland hypersecretion conditions

• name the HPA axis hypersecretion condition

  • name the hyposecretion condition

• the tumour itself can produce the hormone or the endocrine gland can

• acromegaly, cushings, prolactinoma

• cushings

  • addisons

• what are the two HPT axis conditions

• what is the HPG one

• hyper and hypothyroidism

• HPG dysfunction